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    Subject[PATCH 3.10 18/58] inet: prevent leakage of uninitialized memory to user in recv syscalls
    Date
    3.10-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Hannes Frederic Sowa <hannes@stressinduktion.org>

    [ Upstream commit bceaa90240b6019ed73b49965eac7d167610be69 ]

    Only update *addr_len when we actually fill in sockaddr, otherwise we
    can return uninitialized memory from the stack to the caller in the
    recvfrom, recvmmsg and recvmsg syscalls. Drop the the (addr_len == NULL)
    checks because we only get called with a valid addr_len pointer either
    from sock_common_recvmsg or inet_recvmsg.

    If a blocking read waits on a socket which is concurrently shut down we
    now return zero and set msg_msgnamelen to 0.

    Reported-by: mpb <mpb.mail@gmail.com>
    Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
    Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    net/ieee802154/dgram.c | 3 +--
    net/ipv4/ping.c | 9 ++++-----
    net/ipv4/raw.c | 4 +---
    net/ipv4/udp.c | 7 +------
    net/ipv6/raw.c | 4 +---
    net/ipv6/udp.c | 5 +----
    net/l2tp/l2tp_ip.c | 4 +---
    net/phonet/datagram.c | 9 ++++-----
    8 files changed, 14 insertions(+), 31 deletions(-)

    --- a/net/ieee802154/dgram.c
    +++ b/net/ieee802154/dgram.c
    @@ -315,9 +315,8 @@ static int dgram_recvmsg(struct kiocb *i
    if (saddr) {
    saddr->family = AF_IEEE802154;
    saddr->addr = mac_cb(skb)->sa;
    - }
    - if (addr_len)
    *addr_len = sizeof(*saddr);
    + }

    if (flags & MSG_TRUNC)
    copied = skb->len;
    --- a/net/ipv4/ping.c
    +++ b/net/ipv4/ping.c
    @@ -626,7 +626,6 @@ static int ping_recvmsg(struct kiocb *io
    size_t len, int noblock, int flags, int *addr_len)
    {
    struct inet_sock *isk = inet_sk(sk);
    - struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
    struct sk_buff *skb;
    int copied, err;

    @@ -636,9 +635,6 @@ static int ping_recvmsg(struct kiocb *io
    if (flags & MSG_OOB)
    goto out;

    - if (addr_len)
    - *addr_len = sizeof(*sin);
    -
    if (flags & MSG_ERRQUEUE)
    return ip_recv_error(sk, msg, len);

    @@ -660,11 +656,14 @@ static int ping_recvmsg(struct kiocb *io
    sock_recv_timestamp(msg, sk, skb);

    /* Copy the address. */
    - if (sin) {
    + if (msg->msg_name) {
    + struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
    +
    sin->sin_family = AF_INET;
    sin->sin_port = 0 /* skb->h.uh->source */;
    sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
    memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
    + *addr_len = sizeof(*sin);
    }
    if (isk->cmsg_flags)
    ip_cmsg_recv(msg, skb);
    --- a/net/ipv4/raw.c
    +++ b/net/ipv4/raw.c
    @@ -692,9 +692,6 @@ static int raw_recvmsg(struct kiocb *ioc
    if (flags & MSG_OOB)
    goto out;

    - if (addr_len)
    - *addr_len = sizeof(*sin);
    -
    if (flags & MSG_ERRQUEUE) {
    err = ip_recv_error(sk, msg, len);
    goto out;
    @@ -722,6 +719,7 @@ static int raw_recvmsg(struct kiocb *ioc
    sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
    sin->sin_port = 0;
    memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
    + *addr_len = sizeof(*sin);
    }
    if (inet->cmsg_flags)
    ip_cmsg_recv(msg, skb);
    --- a/net/ipv4/udp.c
    +++ b/net/ipv4/udp.c
    @@ -1207,12 +1207,6 @@ int udp_recvmsg(struct kiocb *iocb, stru
    int is_udplite = IS_UDPLITE(sk);
    bool slow;

    - /*
    - * Check any passed addresses
    - */
    - if (addr_len)
    - *addr_len = sizeof(*sin);
    -
    if (flags & MSG_ERRQUEUE)
    return ip_recv_error(sk, msg, len);

    @@ -1274,6 +1268,7 @@ try_again:
    sin->sin_port = udp_hdr(skb)->source;
    sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
    memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
    + *addr_len = sizeof(*sin);
    }
    if (inet->cmsg_flags)
    ip_cmsg_recv(msg, skb);
    --- a/net/ipv6/raw.c
    +++ b/net/ipv6/raw.c
    @@ -459,9 +459,6 @@ static int rawv6_recvmsg(struct kiocb *i
    if (flags & MSG_OOB)
    return -EOPNOTSUPP;

    - if (addr_len)
    - *addr_len=sizeof(*sin6);
    -
    if (flags & MSG_ERRQUEUE)
    return ipv6_recv_error(sk, msg, len);

    @@ -500,6 +497,7 @@ static int rawv6_recvmsg(struct kiocb *i
    sin6->sin6_flowinfo = 0;
    sin6->sin6_scope_id = ipv6_iface_scope_id(&sin6->sin6_addr,
    IP6CB(skb)->iif);
    + *addr_len = sizeof(*sin6);
    }

    sock_recv_ts_and_drops(msg, sk, skb);
    --- a/net/ipv6/udp.c
    +++ b/net/ipv6/udp.c
    @@ -373,9 +373,6 @@ int udpv6_recvmsg(struct kiocb *iocb, st
    int is_udp4;
    bool slow;

    - if (addr_len)
    - *addr_len = sizeof(struct sockaddr_in6);
    -
    if (flags & MSG_ERRQUEUE)
    return ipv6_recv_error(sk, msg, len);

    @@ -461,7 +458,7 @@ try_again:
    ipv6_iface_scope_id(&sin6->sin6_addr,
    IP6CB(skb)->iif);
    }
    -
    + *addr_len = sizeof(*sin6);
    }
    if (is_udp4) {
    if (inet->cmsg_flags)
    --- a/net/l2tp/l2tp_ip.c
    +++ b/net/l2tp/l2tp_ip.c
    @@ -518,9 +518,6 @@ static int l2tp_ip_recvmsg(struct kiocb
    if (flags & MSG_OOB)
    goto out;

    - if (addr_len)
    - *addr_len = sizeof(*sin);
    -
    skb = skb_recv_datagram(sk, flags, noblock, &err);
    if (!skb)
    goto out;
    @@ -543,6 +540,7 @@ static int l2tp_ip_recvmsg(struct kiocb
    sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
    sin->sin_port = 0;
    memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
    + *addr_len = sizeof(*sin);
    }
    if (inet->cmsg_flags)
    ip_cmsg_recv(msg, skb);
    --- a/net/phonet/datagram.c
    +++ b/net/phonet/datagram.c
    @@ -139,9 +139,6 @@ static int pn_recvmsg(struct kiocb *iocb
    MSG_CMSG_COMPAT))
    goto out_nofree;

    - if (addr_len)
    - *addr_len = sizeof(sa);
    -
    skb = skb_recv_datagram(sk, flags, noblock, &rval);
    if (skb == NULL)
    goto out_nofree;
    @@ -162,8 +159,10 @@ static int pn_recvmsg(struct kiocb *iocb

    rval = (flags & MSG_TRUNC) ? skb->len : copylen;

    - if (msg->msg_name != NULL)
    - memcpy(msg->msg_name, &sa, sizeof(struct sockaddr_pn));
    + if (msg->msg_name != NULL) {
    + memcpy(msg->msg_name, &sa, sizeof(sa));
    + *addr_len = sizeof(sa);
    + }

    out:
    skb_free_datagram(sk, skb);



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